By virtue of its high rotational precision and silence, a fluid dynamic bearing device can be suitably used in a small motor such as a spindle motor for an information apparatus such as a magnetic disk drive like an HDD, an optical disk drive for a CD-ROM, CD-R/RW, DVD-ROM/RAM or the like, or a magneto-optical disk drive for an MD, MO or the like, as a polygon scanner motor of a laser beam printer (LBP), as a motor for a projector color wheel, or as a fan motor for cooling an electrical apparatus or the like.
For example, the fluid dynamic bearing device (dynamic pressure bearing device) disclosed in Patent Document 1 includes the housing opened at both ends, the bearing sleeve arranged along the inner periphery of the housing, the shaft member inserted along the inner periphery of the bearing sleeve, and the lid member for closing the opening portion at the one end of the housing. The lid member is formed in a substantially disk shape, and the outer peripheral surface thereof is fixed to the inner peripheral surface of the housing.    Patent Document 1: JP 2005-337490 A